Apparatus for producing nonwoven fabric



March 19, 1963 F. KALWAITES APPARATUS FOR PRODUCING NONWOVEN FABRIC 4Sheets-Sheet 1 Filed June 12, 1957 mum March 19, 1963 F. KALWAITESAPPARATUS FOR PRODUCING NONWOVEN FABRIC 4 Sheets-Sheet 2 Filed June 12,1957 March 19, 1963 F. KALWAITES Filed June 12. 1957 APPARATUS FORPRODUCING NONWOVEN FABRIC 4 Sheets-Sheet 3 March 19, 1963 F. KALWAITES3,081,501

APPARATUS FOR PRODUCING NONWOVEN FABRIC Filed June 12. 1957 4Sheets-Sheet 4 f J A Mam/ Mum United States Patent 3,081,501 APPARATUSFOR PRODUCING NONWOVEN FABRIC Frank Kalwaites, Highland Park, N.J.,assignor, by mesne assignments, to Johnson & Johnson, New Brunswick,N..I., a corporation of New Jersey Filed June 12, 1957, Ser. No. 665,2296 Claims. (Cl. 19-161) This invention relates to apparatus for producingnonwoven fabrics, i.e., fabrics produced directly from fibers withoutthe use of conventional spinning, weaving, or knitting operations.

Heretofore, nonwoven fabrics have been essentially different instructure from fabrics which have been woven or knitted. In a woven orknitted fabric, the fibers of the material making up the fabric do notoccur individually, but are twisted into yarns or threads which in turnare woven or knitted into the fabric. In the well-known spinningoperation, fibers are spun or twisted together tightly into mechanicaland frictional engagement with one another to form yarns which aresubstantially circular in cross section. It is these yarns, not thefibers acting individually, which serve as the structural members of theresulting woven or knitted fabrics. Generally speaking, these fabricscomprise reticular structures of intersecting, intertwining yarns whichdefine interstices between them.

Nonwoven fabrics have been of two main types, felts and bonded webs. Ineach of these, the fibers making up the fabric occur individually andact individually as structural members. This is true even though thefibers in many felts are so highly interlocked and compressed togetherthat it is difficult to identify individual fibers. Hat felts, forinstance, are extremely dense, relatively hard fabrics Without apparentinterstices, which are quite dissimilar in appearance and qualities towoven or knitted structures.

On the other hand, the fibers in bonded webs are usually flatlyassembled in layers, either more or less oriented in one direction as ina card web or arranged in a random manner as in an air laid isotropicweb. Various bonding agents have been used to print a binder pattern onsuch webs or to impregnate them to hold the individual fibers together.In this type of fabric, the fibers may remain relatively straight andoverlapping one another with verylittle interlocking between them. Theyare usually arranged in a more or less uniformly spaced condition in theplane of the Web, in such a way that only very small randomly occurringinterstices are apparent between the overlapped fibers and those fibersbetween interstices remain spaced and more or less flatly arranged,possessing little similarity to the yarns of Woven or knitted fabrics.

The present invention contemplates a nonwoven fabric wherein the fibersare arranged to define a predetermined pattern of holes or openings withmost of the fiber segments bordering the holes extending in substantialparallelism with portions of the perimeters of the holes. I11 general,the fibers are arranged in interconnected groupings or web areasextending between the holes in a predetermined pattern corresponding tothe aforementioned pattern of holes. The resulting fabric may be made toresemble a particular woven or knitted fabric.

The groupings or groups are connected by fibers extending from one toanother in such a way that they are common to a plurality of groupings.It is preferred that the average length of the fibers be considerablygreater than the lengths of the groups containing them with the resultthat the groups predominantly comprise only parts or segments of thefibers passing through them. Preferably, the fibers averagerat leastabout 4 inch in length and are textile-like in nature. In general, thegroupings are connected at junctures wherein the fibers extend in aplurality of diverse directions, while the fiber segments in the groupsare relatively parallelized with respect to one another and more closelyassembled than at the junctures.

In the foraminous structure formed by the interconnected fiber groupingsthe fibers are in a state of mechanical equilibrium. The fibers aremechanically and frictionally engaged to the extent that the arrangementof fibers is one of equilibrium.

Due to their structure and appearance and other qualities, fabricsproduced by the method and apparatus of this invention are particularlyadapted for use in surgical dressings, absorbent dressings such assanitary napkins and diapers, most suitably for covering sanitarynapkins and diapers, in wiping cloths, toweling, filter materials,lining materials, industrial base fabrics, as a substitute for gauze andgauze-like fabrics in general, and a variety of other applications.

The present invention contemplates a method and an apparatus forproducing a nonwoven fabric having a predetermined pattern from a layerof irregularly arranged fibers by first wetting the fibrous layer out,then impaling the layer upon a group of prongs, and finally brushing thefibers into fiber accumulating Zones between the prongs.

The layer may be a nonwoven web of fibers, for example, fibers of rayonor cotton. The individual fibrous elements of the layer are capable ofmovement under the influence of an applied mechanical force. In general,the starting material of the method herein described may be any of thestarting materials described in the Kalwaites Patent No. 2,862,251,granted December 2, 1958. The preferred starting material is an unbondedfibrous web.

The preferred method of this invention involves the application ofexternal forces to a continuously moving layer of irregularly arrangedfibers impaled upon a group of prongs, by simultaneously brushing thefibers of successive portions of the moving layer longitudinally andtransversely of the direction of travel of the layer, thereby movingindividual fiber segments into positions within fiber accumulating Zonesin the interconnected spaces between the prongs.

In a preferred embodiment of the apparatus of this invention, the prongsor needles are carried on a rotatable cylinder against which a movinglayer of irregularly arranged fibers is positioned. The layer of fibersis first passed through a pair of wet-out rolls and then into engagementwith the pointed ends of the needles. An embedding brush is reciprocatedin a direction normal to the peripheral surface of the cylinder, topress successive portions of the advancing layer of fibers downwardlyabout the needles. The reciprocation of the embedding brush iscontrolled by an eccentric bearing which permits only an instantaneouscontact with the moving layer of fibers, since the embedding brush mustbe lifted from the fibers immediately because the needle-bearingcylinder is rotated continuously. The embedding brush is pivoted topermit it to move with the cylinder for the very short interval duringwhich itis in contact with the layer of fibers.

Therotation of the cylinder pulls each portion of the layer of fibersprogressively past a seriesof rotary brushes disposed at right angles tothe direction of travel of the layer, with their bristles in contactwith the layer of fibers embedded about the needles. Alternate brushesare rotated in opposite directions from the direction of rotation of thebrushes intermediate the alternate brushes. These rotary brushes pressthe fibers downwardly about the needles, toward the peripheral surfaceof the cylinder.

The rotary brushes, which are parallel to the longitudinal axis of thecylinder, are also oscillated longitudinally of the cylindersimultaneously with their rotational movement. The combined rotationaland oscillatory movements of the rotary brushes move the individualfibers of the layer along the tapered sides of the needles into contactwith the peripheral surface of the cylinder, laterally into the spacesbetween the needles, and in the direction of their respectivelongitudinal axes, with respect to the other fibers in the layer, tocompact them in fiber accumulating zones between the needles.

The water which is added to the layer of fibers by the wet-out rolls asthe layer is moved through the nip between them acts as a lubricant andfacilitates the relative movement between the individual fibers in thedirection of their respective longitudinal axes. The relativelongitudinal movement between individual fibers places the fibers inmechanical equilibrium in their rearranged positions in the resultingnonwoven fabric.

The resulting nonwoven fabric is removed from the needles by passing itthrough the nip between a pair of doffing rolls positioned beyond thelast of the rotary brushes. Either one of the dofiing rolls may bedriven to insure continuous movement of the nonwoven fabric away fromthe cylinder, or suitable means may be provided beyond the dofiing rollsto carry the nonwoven fabric into a drying area. It is obvious that thedriven dotfer roll or means for moving the nonwoven fabric from thecylinder to the drying area must be synchronized with thecricumferential speed of the cylinder.

The prongs upon which the fibrous starting layer is impaled before thebrushing action is carried out may have rounded, flat, or pointed ends.They are preferably formed with a cylindrical body and long, graduallytapered conical points at their free ends. Conventional card clothing,with the customary burrs removed from the free ends, may also be used.Needles of various sorts are also suitable, including needles havingbodies of various cross-sectional shapes, with chisel shaped free ends.

Advantages of the invention other than those generally described abovewill be apparent from the following description and claims, takentogether with the drawings wherein:

FIGURE 1 is a side view, partially in section and partly in elevation,of a machine embodying the invention, with a portion of the frameremoved to clarify the illustration, the feed end of the machine beingshown on the left and the discharge end on the right side of the figure;

FIG. 2 is a fragmentary cross sectional view, taken along the line 22 ofFIG. 1;

FIG. 3 is a fragmentary elevation of the feed end of the machine, withthe structure outside the side frame members generally omitted;

FIG. 4 is a fragmentary detail view, partly in elevation and partly insection, showing the embedding brush and the means for reciprocating italong a line normal to the peripheral surface of the cylinder;

FIG. 5 is a cross sectional view, taken along the line 5-5 of FIG. 4;

FIG. 6 is a fragmentary elevational view of the right side of themachine as seen in FIG. 2, showing the driving mechanism for rotatingthe rotary brushes; and

FIG. 7 is a fragmentary elevational view of the left side of the machineas seen in FIG. 2, showing the mechanism for oscillating the rotarybrushes longitudinally of the cylinder.

In the drawings, the reference numeral 2 indicates a supporting framecomprising a pair of vertical posts 3 on opposite sides of the frame atthe feed end of the machine and a pair of vertical posts 4 on oppositesides of the discharge end. Longitudinal beams '5 connect each verticalpost 3 to the vertical post 4 on the same side of the machine. Atransverse beam 5 connects the vertical posts 3 at the feed end of themachine, and a similar transverse beam connects the vertical posts 4-.The frame also includes a side frame plate 6 extending vertically upwardfrom the longitudinal beam 5 at the right side of the frame (as seenfrom the feed end) and a similar side frame plate 7 extending verticallyupward from the beam 5 at the left side of the frame.

A conveyor 8 is positioned adjacent the feed end of the machine to carrya layer 9 of irregularly arranged fibers to the feed end of the machine.The layer of fibers may or may not be self-sustaining. If it is notself-sustaining, a permeable carrier web is provided to carry it untilsuch support is no longer required.

A conveyor 10 is positioned adjacent the discharge end of the machinefor carrying the nonwoven fabric, in which the fibers of the layer havebeen rearranged in a predetermined pattern, from the machine to asuitable bonding or drying area (not shown) of a conventional type. Thespecific structure of the conveyors 3 and 10 is not described, sincethey do not constitute part of the invention and may be of conventionalconstruction.

Wet-out rolls 11 and 12, extending transversely of the machine, arerotatably mounted in vertical alignment at the feed end of the machine.A shaft 13, carrying wetout roll 11, is journalled in bearings 14mounted on each vertical post 3.

Lower wet-out roll 11 is partially immersed in a water pan 15 supportedon brackets 16 mounted on each post 3 below the bearings 14. Upperwet-out roll 12 is carried by a shaft 17 journalled in bearings 18. Eachbearing 18 is slidably mounted in a recess 19 extending verticallydownward from the upper edge of each vertical post 3. The verticalposition of upper wet-out roll 12 is adjustable, and is regulated byhydraulic positioning cylinders 20 mounted on brackets 21 projectinglaterally from the top of vertical posts 3. Each positioning cylinderhas a two-way piston (not shown) carrying a piston rod 22 connected atits lower end to the bearing 18. By applying hydraulic pressure throughconventional control means to one side or the other of the piston ofeach positioning cylinder, the pressure at the nip between wet-out rolls11 and 12 may be varied as desired.

The pair of wet-out rolls 11 and 12 cooperate to control the moisturecontent of the layer 9 of irregularly arranged fibers which is fed fromconveyor 8 through the nip between the wet-out rolls. The position ofroll 12, relative to roll 11, determines the quantity of water that isapplied to the layer 9. The fibers of layer 9 are in mechanical andfrictional engagement with one another as the layer passes through thenip between the wet-out rolls. Preferably the layer of fibers containsin the neighborhood of to 200 percent moisture as it leaves the wet-outrolls. The term percent moisture, when used in this specification,refers to the percentage of moisture by weight of the dry layer offibers.

A main drive shaft 23, extending transversely between side frame plates6 and 7, is journalled in bearings 24 each mounted on one of thelongitudinal beams 5. The drive shaft projects outside each side frameplate for reasons hereinafter disclosed. A cylinder 25 mounted on driveshaft 23 to rotate therewith is provided with a plurality of needles 26or similar sharp tapered implements projecting radially from itsperipheral surface. The needles are secured to the surface of thecylinder in any suitable manner, and are arranged in accordance with thepredetermined pattern of the fabric to be made from the layer ofirregularly arranged fibers. During the operation of the machine thedrive shaft rotates the needle bearing cylinder 25 continuously.

From the nip between the wet-out rolls 11 and 12, the layer 9 ofirregularly arranged fibers is moved into contact with the sharp ends ofthe needles projecting radially from the peripheral surface of thecylinder. The layer of fibers is pulled into contact with the sharppointed ends of the needles in an area of the peripheral surface of thecylinder in which pressure means, such a an embedding brush 27, isadapted to impale the layer of fibers on the needles.

The embedding brush 27 extends longitudinally of the needle bearingcylinder and covers substantially the entire width of the cylinder. Theworking surface of the embedding brush, formed by the ends of the brushbristles, is substantially fiat, but is curved slightly in itstransverse direction to allow it to conform to the circumferentialcurvature of the needle bearing cylinder. The brush 27 comprises aplurality of soft bristles 28 secured to a back 29 which is pivotallysecured, as indicated at 30, to a clevis 31 formed on the lower end of areciprocating rod 32. The axis of the pivot pin 30 is parallel to thelongitudinal aXis of main drive shaft 23 for a reason hereinafterdisclosed.

A cross bar 33 extending transversely of the machine has its oppositeends secured adjacent the upper edges of the side frame plates 6 and 7.A plurality of supporting :arms 34 secured to cross bar 33 dependtherefrom to rotatably support an embedding brush drive shaft 35extending parallel to bar 33, as shown in FIGS. 4 and 5. The arms 34,and the associated mechanism, are equivalents, and only one Will bedescribed. The shaft 35 is driven by any suitable driving means (notshown) and carries a pair of eccentric bearings 36 thereon. Each bearingcomprises a disk 37 eccentrically keyed to shaft 35, as indicated at 38,and a circular strap 39 fitting around the rim of disk 37. Rollerbearings 40, mounted in a race between the peripheral surface of disk 37and the contiguous inner surface of the circular strap 39, permit thedisk 37 to rotate relative to the strap 39, while the eccentricity ofthe disk relative to shaft 35 causes the circular strap 39 toreciprocate. One end 41 of rod 32 is threaded to fit into a threadedrecess 42 formed in the strap 39, whereby rod 32 will be reciprocated bythe reciprocating movement of strap 39.

In order to keep reciprocating rod 32 moving back and forth in a fixedpath, a guide support cross bar 43-, having its opposite ends secured toside frame plates 6 and 7, is mounted parallel to embedding brush driveshaft 35, between that shaft and cylinder 25. Cross bar 43 has a guideopening 44, extending normal to the peripheral surface of cylinder 25,which is provided with a guide bearing sleeve 45. Reciprocating rod 32is positioned in the guide bearing sleeve with a sliding fit so that itcan move only in a direction normal to the peripheral surface of needlebearing cylinder 25.

It is seen that rotation of embedding brush drive shaft 35 imparts tothe embedding brush 27 a reciprocatory motion having a stroke equal totwice the eccentricity of eccentric bearing 36. Due to the guide supportsystem just described, the reciprocatory motion is confine-d to a pathnormal to the peripheral surface of cylinder 35.

The reciprocating movement of the embedding brush 27 causes the bristles28 to engage the layer 9 of fibers and press it downwardly upon theneedles 26. The layer of fibers is constantly moving with the needles ofcylinder 25, and the bristles of the embedding brush remain inengagement with the layer of fibers for only a very short interval oftime. The pivotal joint 30 connecting the bottom end of reciprocatingrod 32 and brush 27 permits the embedding brush to pivot and move withthe needles the slight distance the needle bearing cylinder rotatesduring the interval the embedding brush is in contact with the needles.When the embedding brush is lifted out of engagement with the needles bythe upward stroke of its reciprocatory improvement, gravity will causethe brush to fall back pivotally, again about joint 30, into it originalof fibers produces the major fiber rearrangement as the fibrous layer isimpaled upon the needles. In this first rearranging step the fibers arepushed out of the local areas of the layer which are occupied by theadvancing needles. As a result, fibers are pushed into closer proximityand increased parallelism in the areas bordering upon the needles. Therearrangement of the fibers is completed by the brushing action ofrotary brushes 46, 47, 48, and 49, now to be described.

As the embedding brush 27 moves upwardly out of engagement with thelayer of fibers, the layer, which is now impaled firmly on needles 26,is moved by the needles past a series of rotary brushes 46, 47, 48 and49 mounted on independent drive shafts 50, 51, 52, and 53, respectively.In the embodiment shown, the rotary brush drive shafts 50, 51, 52, and53 are spaced substantially equidistant from main drive shaft 23 and areso positioned relative to the peripheral surface of needle bearingcylinder 25 as to maintain the bristles 54, 55, 56, and 57 of the rotarybrushes 46, 47, 4-8, and 49, respectively, in engagement with the fibersof a portion of layer 9 as the layer passes between the needle bearingcyinder and the rotary brushes. The bristles of each of the rotarybrushes are very soft so that they may rearrange the fibers of layer 9without destroying the in tegrity of the layer. As is seen in FIG. 1,some of the bristles are long enough thatexcept as they are pre ventedfrom doing so by the presence of the fibrous web being rearranged-theyextend between the spaced needles 26 and below the free side of thoseneedles.

-As shown in FIG. 6, independent drive belts 58, 59, 60 and 61 extendaround a pulley 62 mounted on main drive shaft 23 and pulleys 63, 64,65, and 66 mounted on rotary brush drive shafts 50, 51, 52, and 53,respectively. The drive belts 58, 59, 6t), and 61 drive the shafts 50,51, 52, and 53 from main drive shaft 23. -As shown in FIG. 2, theopposite ends of each of the rotary brush shafts 50, 51, 52, and 53 aremounted in bearings (not shown) carried by bearing supports 67 and 68mounted on the outer surfaces of side frame plates 6 and 7, re-.spectively.

The drive belts 58 and 60 are each crossed between pulley 62 and theirrespective pulleys 63 and to drive rotary brushes 46 and 48 in theopposite direction to the direction of rotation of rotary brushes 47 and4-9. From the, arrows in FIG. 1 indicating the direction of rotation ofthe needle bearing cylinder and each of the rotary brushes, it is seenthat the rotary brushes 46 and 48 are driven in the opposite directionfrom that in which the needle bearing cylinder 25 is driven, and thatrotary brushes 47 and 49 are driven in the same direction as thecylinder 25. Since the rotary brush drive shafts 50, 51, 52, and 53 areeach outside the periphery of the needle bearing cylinder 25, bristles54 and 56 of rotary brushes 46 and 48, respectively, travel in the samedirection as the needles 26 during the portion of their rotationalmovement while they are in contact with said needles, and bristles 55and 57 of rotary brushes 47 and 49 travel in the opposite direction fromneedles 26 While they are in contact with the needles.

The effective fiber rearranging forces exterted by the bristles of eachbrush as a result of the rotational movement of the brushes depends uponthe difference between the linear speed of the bristles and the linearspeed of the fibrous layer 9 in the area of contact between them. Thisdifference between the linear speeds of the bristles and the fibers isobtained by subtracting the linear speed of the layer 9 from the linearspeed of bristles 54 and 56 which are moving in the same direction, andadding the linear speed of the layer 9 to the linear speed of bristles55 and 57 which are moving in opposite directions. The rotation ofrotary brushes 46 and 48, upon which bristles 54 and 56 are carried, maybe speeded up to obtain equal fiber rearranging forces for each of therotary brushes.

Additional fiber rearranging forces are applied to the fibers of layer 9by longitudinal oscillation of the shaft of each of the rotary brushes.The mechanism for oscillating the shafts of the rotary brusheslongitudinally of their respective axes is shown in FIGS. 2 and 7. Themechanism is the same for each rotary brush, and the description thereofwill generally be limited to a single rotary brush for the sake ofbrevity.

A worm 69 extending laterally from a sleeve 79 is mounted on the end ofdrive shaft 23 extending outwardly beyond the side frame plate 7. Theworm is preferably integral with sleeve 70, but may be formed separatelyand rigidly secured thereto in any suitable manner. Worm 69 meshes witha worm wheel 71 fixed on oscillator drive shaft 72 which is rotatablymounted in a plurality of bearings 73 extending outwardly from sideplate frame 7. Four oscillator earns 74 are rigidly mounted in eccentricrelationship on oscillator drive shaft 72. The cams 74 are spacedlongitudinally of oscillator drive shaft 72 for a purpose hereinafterdescribed. Collars 75 and 76 are fixed to opposite ends of shaft 72 toprevent displacement of the shaft along its axis relative to worm wheel71 and bearings 73.

Each bearing support 68 has a pair of fulcrum arms 77 extendingoutwardly therefrom, and an oscillator lever 78 is pivoted between eachpair of fulcrum arms as indicated at 79. The pivot is positioned betweenthe horizontal planes of shaft 72 and the particular rotary brush driveshaft 50, 51, 52, or 53 which is supported by the bearing in the bearingsupport 68 from which the fulcrum arms supporting the pivot extend. Eachoscillator lever 78 has sufiicient length to extend from a pointadjacent oscillator drive shaft 72 to a point adjacent the end of therespective rotary brush drive shaft 50, 51, 52, and 53.

The lower end of each oscillator lever 78 is bifurcated, as indicated at30, and a follower roller 81 is mounted to rotate freely on a pin 82extending across the bifurcated end of the oscillator lever. The cams 74are spaced in alignment with follower rollers 81, and each roller 81 isnormally held in contact with the periphery of one of the earns 74. Eachrotary brush drive shaft 50, 51, 52, and 53 has a mollar 83 securedadjacent its end and a compression spring 84 coiled around the shaft isbiased between the collar and a shoulder 85 on the bearing support 68 toexert a constant force against collar 83 to urge the shaft outwardlyinto contact with the upper end of the respective oscillator lever 78.

As the main drive shaft 23 is rotated, it causes oscillator drive shaft72 to rotate through the gear linkage, already described, and therebymove each of the oscillator cams 74 through its eccentric orbit. As eachcam '74 moves outwardly, it presses against its associated followerroller 81, moving the upper end of the respective oscillator lever '78and rotary brush drive shaft i Sll, 52, and 53 inwardly against theaction of compression spring 84. As the cam 74 moves inwardly, thespring 34 pushes the rotary brush drive shaft outwardly to complete thelongitudinal oscillation of the shaft. Each rotary brush completes anoscillatory cycle for every revolution of oscillator drive shaft 72.

If the rearranging forces are applied to an isotropic fibrous web onlyin a direction parallel to the direction of web travel, they will actmost eflectively on fibers extending at right angles to the direction ofweb travel and will have virtually no effect on fibers extendingparallel to the direction of web travel. The effectiveness of therearranging forces will vary for fibers in intermediate positions, withthe effectiveness increasing with any increase in the angle of fiberorientation to the direction of web travel.

It is seen that rearrangement of the fibers could not be uniform if therearranging forces were applied in only one direction, because of thediminished rearrangement of fibers as the angle of orientation of thefibers approaches the angle of direction of the applied forces.Therefore, the best results are obtained by applying the samerearranging forces in all directions. In the apparatus of this inventionrearranging force components having the same effective magnitude areapplied to the fibers in all four directions at right angles to eachother.

The rearranging force applied by each rotary brush to the fibers oflayer 9 is a resultant of forces produced by the above-describedoscillation and by the rotation of the shaft on which the rotary brushis mounted. If one plots the motion of each brush with respect to layer9 due to the oscillation of the brush shaft, the graph will be in theform of a sinusoidal curve. A graph of the motion of a particular groupof bristles on the brush with respect to layer 9 due to rotation of thebrush will have the form of a straight line. To determine the resultantfiber rearranging force produced by both the rotation and theoscillation of a particular rotary brush 54, 55, 56, or 57, the forcedue to the circumferential movement of the brush with respect to thefibers, which is of substantially constant magnitude, must be combinedwith the varying force due to shaft oscillation.

At a given moment, the force applied to the fibers in any particulardirection by the rotating and oscillating brush is proportional to therelative speed of movement of the brush in that direction with respectto the fibers. This is true both of the rearranging force produced byrelative movement of the brush bristles and the fibers due to retationof the brush, and of the rearranging force produced by relative movementof the brush bristles and fibers due to oscillation of the brush shaft.

The linear speed of movement of the bristles with respect to the fiberswhich is due to brush rotation may be computed for bristles 54 and 56 onthe one hand, and bristles 55 and 57 on the other, in the manner alreadydescribed above. Since the relative speed of bristles and fibers due torotation of a given brush remains substantially constant, the magnitudeof the resulting fiber rearranging force component likewise remainssubstantially constant during normal operation of the machine of thisinvention.

The speed of movement of the brush due to oscillation of its shaftvaries, however, as the shaft passes through its oscillatory c cle. Thisspeed may be represented by a sinusoidal curve out of phase with thecurve representing the oscillatory morion of the shaft. In the same way,the resulting fiber rearranging force may also be represented by asinusoidal curve 90 out of phase with the curve showing the oscillatorymotion of the shaf During one half the cycle, the force componentproduced by the oscillation of the rotary brush drive shaft is appliedin one direction transverse to the direction of web travel, and duringthe next half of the cycle it is applied in the opposite direction. Theforce component is of continuously varying magnitude, increasing fromzero at each outer limit of the cycle of oscillation to a maximum whenthe shaft passes through its middle position and the sinusoidal curverepresenting the oscillatory movement of the shaft passes through itsnode. The component of force then decreases until the shaft reaches theopposite outer limit of its oscillation, when the direction of the forcecomponent is reversed.

The brushing force component produced by the oscillation of the rotarybrush drive shaft is thus generally sinusoidal. However, the nature ofthe brushes tends to cause the sine curve representing the brushingforce component to be flattened out somewhat at each peak. Sincebristles 54, 55, 56, and 57 of the rotary brushes are preferably softand limber, the bristles will tend to bend and their free ends to lagbehind the body of the brush as it moves back and forth. When the brushdrive shaft reverses its direction of longitudinal movement at each endof its cycle, the bristle ends exhibit an even greater lag, for theythen tend to stop altogether, and to remain stationary until the brushbody has moved back in the reverse direction far enough to pick up theslack due to the bending of the bristles. Hence the sine curverepresenting the force component caused by oscillation of the driveshaft must be drawn with each peak flattened out somewhat rather thanrising to the maximum value for a perfect sine curve.

It is seen that the effective rearranging force component applied to thefibers in one direction parallel to the axis of each rotary brush may beapproximated by determining What may be called a root mean square force,by analogy to the computation of the root mean square voltage of analternating electric current. By root mean square is meant a quantityequal to 0.707 of the maximum amplitude of the sinusoidal curverepresenting that rearranging force.

The effective rearranging force component applied to the fibers in theopposite transverse direction has the same magnitude but opposite sign.It is seen that the root mean square or effective transverse rearrangingforce is applied in each direction parallel to the rotary brush axisduring only one half the operation of the machine, and in the oppositedirection during the other half of the period of operation. However, therearranging force in each transverse direction is supplemented, in theembodiment of the machine shown and described, by the force applied bythe adjacent rotary brush, which passes through the same cycle ofoscillation and produces the same transverse rearranging force first inone direction and then the other.

To produce most nearly uniform rearrangement of the fibers, therearranging force applied by each rotary brush should have a componentparallel to the direction of web travel whose magnitude is substantiallyequal to the effective magnitude of the force component applied first inone direction parallel to the direction of shaft oscillation and then inthe opposite. The force applied to the fibers by the rotary brush at anymoment is proportional to the relative speed of movement of the rotarybrush with respect to the fibers. Therefore, whenever each rotary brushrotating in one direction (such as brushes 46 and 48 in the embodimentshown and described) is supplemented by another brush (such as brushes47 and 49) rotating in the opposite direction, the linearcircumferential speed of each brush in relation to the fibers beingrearranged is preferably equal to 0.707 of the maximum speed of theoscillating rotary brush drive shaft as it passes through the midpointin its oscillatory path.

As mentioned above, the initial impaling step produces the majorrearrangement of the fibers of the fibrous starting layer into anonwoven fabric 9, having a pattern of openings corresponding to thearrangement of the needles on the needle bearing cylinder. Thecumulative effect of brushing the fibers between the needles indifferent directions, as just described, completes that rearrangement.More specifically, the brushing step supplements the initial lateralmovement of the fibers produced by penetration of the prongs or needles,by causing individual fibers to move in the direction of theirrespective longitudinal axes, with respect to the other fibers in thelayer, and thereby to lie in mechanical equilibrium in their finalrearranged positions.

After the resulting nonwoven fabric passes the last rotary brush at thedischarge end of the machine, it is removed from the cylinder by passingit between the nip of a pair of dofiing rolls 86, 87. The fabric ismoved from the doffing rolls to a conveyor 10* which carries it to asuitable drying or other processing area (not shown). bearings 88, 3carried by the vertical posts and side frame plates at the discharge endof the machine. One of the dofiing rolls is preferably driven by a motor90. The motor 90 also drives the main drive shaft 23 through a belt 91extending around a pulley 92 mounted on one end of the drive shaft.

As used in this specification and claims, the term tapered implementsincludes not only an implement which is tapered from its base to itsfree end but also any implement which has uniform cross-sectionaldimensions throughout its body portion and gradually di- The dotlingrolls are rotatably mounted in 10 minishing cross-sectional dimensionsat its free end portion.

The above-detailed description of this invention has been given forclearness of understanding only. No unnecessary limitations should beunderstood therefrom, as modifications will be obvious to those skilledin the art.

I claim:

1. A machine for continuously producing a nonwoven fabric having holesarranged in a predetermined pattern from a layer of wet, irregularlyarranged fibers, said machine comprising a rotatably mounted cylinder,means to rotate said cylinder, a group of prongs mounted on theperipheral surface of said cylinder, said prongs being arranged in saidpredetermined pattern, means for impaling successive portions of a layerof wet, irregularly arranged fibers upon said prongs to move certain ofsaid fibers laterally into new positions in the layer, a group ofbrushes rotatably mounted adjacent said cylinder with their longitudinalaxes parallel with the longitudinal axis of the cylinder and havingsoft-bristles extending therefrom some of whose end portions, uponrotation of the brushes, are adapted to extend between said prongs andbelow the free ends thereof, and means for rotating various of saidbrushes in different directions to maintain said impaling and moveindividual fibers in the direction of their respective longitudinalaxes, with respect to the other fibers in the layer, so as to permit therearranged fiber segments to remain in a condition of mechanicalequilibrium in their new positions in the areas between the prongs wherethey define said predetermined pattern of holes.

2. A machine for continuously producing a nonwoven fabric having holesarranged in a predetermined pattern from a layer of wet, irregularlyarranged fibers, said machine comprising a rotatably mounted cylinder,means to rotate said cylinder, a group of prongs mounted on theperipheral surface of said cylinder, said prongs be ing arranged in saidpredetermined pattern, means for impaling successive portions of a layerof wet, irregularly arranged fibers upon said prongs to move certain ofsaid fibers laterally into new positions in the layer, a group ofbrush-es rotatably mounted adjacent said cylinder with theirlongitudinal axes parallel with the longitudinal axis of the cylinderand having soft-bristles extending therefrom some of whose end portions,upon rotation of the brushes, are adapted to extend between said prongsand below the free ends thereof, means for rotating various of saidbrushes in different directions, and means for simultaneouslyoscillating said brushes longitudinally of their longitudinal axes, tomaintain said impaling and move individual fibers in the direction oftheir respective longitudinal axes, with respect to the other fibers inthe layer, so as to permit the rearranged fiber segments to remain in acondition of mechanical equilibrium in their new positions in the areasbetween the prongs where they define said predetermined pattern ofholes.

3. A machine for producing a nonwoven fabric having holes arranged in apredetermined pattern from a layer of wet, irregularly arranged fibers,said machine comprising a rotatably mounted cylinder, means to rotatesaid cylinder, a group of prongs mounted on the peripheral surface ofsaid cylinder, said prongs being arranged in said predetermined pattern,means for impaling successive portions of a layer of wet, irregularlyarranged fibers upon said prongs to move certain of said fiberslaterally into new positions in the layer, a group of brushes rotatablymounted adjacent said cylinder with their longitudinal axes parallelwith the longitudinal axis of the cylinder and having soft bristlesextending therefrom some of Whose end portions, upon rotation of thebrushes, are

adapted to extend between said prongs and below the free ends thereof,means for rotating alternate ones of said brushes in a difierentdirection from the direction of rotation of the brushes intermediatesaid alternate brushes, and means for simultaneously oscillating saidbrushes longitudinally of their longitudinal axes, to maintain saidimpaling and move individual fibers in the direction of their respectivelongitudinal axes, with respect to the other fibers in the layer, so asto permit the rearranged fiber segments to remain in a condition ofmechanical equilibrium in their new positions in the areas between theprongs where they define said predetermined pattern of holes.

4. A machine for producing a nonwoven fabric having holes arranged in apredetermined pattern from a layerhof wet, irregularly arranged fibers,said machine comprising a rotatably mounted cylinder, means to rotatesaid cylinder, a group of prongs mounted on the peripheral surface ofsaid cylinder, said prongs being arranged in said predetermined pattern,means for impaling successive portions of a layer of wet, irregularlyarranged fibers upon said prongs to move certain of said fiberslaterally into new positions in the layer, a group of brushes rotatablymounted adjacent said cylinder with their longitudinal axes parallelwith the longitudinal axis of the cylinder and having soft bristlesextending therefrom some of whose end portions, upon rotation of thebrushes, are adapted to extend between said prongs and below the freeends thereof, means for rotating alternate ones of said brushes in adifferent direction from the direction of rotation of the brushesintermediate said alternate brushes, the brushes which turn in the sameangular direction as the rotating cylinder being rotated less rapidlythan the brushes which turn in the opposite direction, and means forsimultaneously oscillating said brushes longitudinally of theirlongitudinal axes, to maintain said impaling and move individual fibersin the direction of their respective longitudinal axes, with respect tothe other fibers in the layer, so as to permit the rearranged fibersegments to remain in a condition of mechanical equilibrium in their newpositions in the areas between the prongs where they define saidpredetermined pattern of holes.

5. A machine for producing a nonwoven fabric having holes arranged in apredetermined pattern from a layer of wet, irregularly arranged fibers,said machine comprising a frame, a cylinder rotatably mounted in saidframe, means to rotate said cylinder, a group of prongs projectingoutwardly from the peripheral surface of said cylinder, said prongsbeing arranged in said predetermined pattern, means for movingsuccessive portions of a layer of wet, irregularly arranged fibers intocontact with the ends of said prongs, an embedding brush mounted in saidframe opposite said cylinder, means for reciprocating said brush in adirection normal to the peripheral surface of said cylinder for impalingsaid successive portions of the layer of fibers on said prongs to movecertain of said fibers laterally into new positions in the layer, saidembedding brush being pivoted to permit limited movement thereof in thedirection of rotation of said cylinder, a group of brushes rotatablymounted adjacent said cylin der and having soft bristles extendingtherefrom some of whose end portions, upon rotation of the brushes, areadapted to extend between said prongs and below the free ends thereof,and means for simultaneously rotating and oscillating said rotarybrushes to maintain said impaling and move individual fibers in thedirection of their respective longitudinal axes, with respect to theother fibers in the layer, so as to permit the rearranged fiber segmentsto remain in a condition of mechanical equilibrium in their newpositions in the areas between the prongs Where they define saidpredetermined pattern of holes.

6. A machine for producing a nonwoven fabric having holes arranged in apredetermined pattern from, a layer of wet, irregularly arranged fibers,said machine comprising a frame, a cylinder rotatably mounted in saidframe, means to rotate said cylinder, a group of implements projectingoutwardly from the peripheral surface of said cylinder, said implementshaving sharp free ends and being arranged in said predetermined pattern,means for moving successive portions of a layer of wet, irregularlyarranged fibers into contact with the ends of said implements, anembedding brush mounted in said frame opposite said cylinder, means forreciprocating said brush in a direction normal to the peripheral surfaceof said cylinder for impaling said successive portions of the layer offibers on said implements, said embedding brush being pivoted to permitlimited movement thereof in the direction of rotation of said cylinder,a group of brushes rotatably mounted adjacent said cylinder and havingsoft bristles extending therefrom some of whose end portions, uponrotation of the brushes, are adapted to extend between said implementsand below the free ends thereof, means for rotating alternate ones ofsaid brushes in a different direction from the direction of rotation ofthe brushes intermediate said alternate brushes, and means forsimultaneously oscillating said brushes longitudinally of theirlongitudinal axes, to maintain said impaling and move individual fibersin the direction of their respective longitudinal axes, with respect tothe other fibers in the layer, so as to permit the rearranged fibersegments to remain in a condition of mechanical equilibrium in their newpositions in the areas between the prongs where they define saidpredetermined pattern of holes.

References Cited in the file of this patent UNITED STATES PATENTS 75,906Haythorn et al. Mar. 24, 1868 355,296 Best Jan. 4, 1887 493,752Clarenbach et al Mar. 21, 1893 7 1,567,841 Curtin Dec. 29, 19251,743,068 Walsh Jan. 7, 1930 1,978,620 Brewster Oct. 30, 1934 2,055,412Hurst et al. Sept. 22, 1936 2,881,505 Hoffman Apr. 14, 1959

1. A MACHINE FOR CONTINUOUSLY PRODUCING A NONWOVEN FABRIC HAVING HOLESARRANGED IN A PREDETERMINED PATTERN FROM A LAYER OF WET, IRREGULARLYARRANGED FIBERS, SAID MACHINE COMPRISING A ROTATABLY MOUNTED CYLINDER,MEANS TO ROTATE SAID CYLINDER, A GROUP OF PRONGS MOUNTED ON THEPERIPHERAL SURFACE OF SAID CYLINDER, SAID PRONGS BEING ARRANGED IN SAIDPREDETERMINED PATTERN, MEANS FOR IMPALING SUCCESSIVE PORTIONS OF A LAYEROF WET, IRREGULARLY ARRANGED FIBRES UPON SAID PRONGS TO MOVE CERTAIN OFSAID FIBERS LATERALLY INTO NEW POSITIONS IN THE LAYER, A GROUP OFBRUSHES ROTATABLY MOUNTED ADJACENT SAID CYLINDER WITH THEIR LONGITUDINALAXES PARALLEL WITH THE LONGITUDINAL AXIS OF THE CYLINDER AND HAVINGSOFT-BRISTLES EXTENDING THEREFROM SOME OF WHOSE END PORTIONS, UPONROTATION OF THE BRUSHES, ARE ADAPTED TO EXTEND BETWEEN SAID PRONGS ANDBELOW THE FREE ENDS THEREOF, AND MEANS FOR ROTATING VARIOUS OF SAIDBRUSHES IN DIFFERENT DIRECTIONS TO MAINTAIN SAID IMALYING AND MOVEINDIVIDUAL FIBERS IN THE DIRECTION OF THEIR RESPECTIVE LONGITUDINALAXES, WITH RESPECT TO THE OTHER FIBRES IN THE LAYER, SO AS TO PERMIT THEREARRANGED FIBER SEGMENTS TO REMAIN IN A CONDITION OF MECHANICALEQUILIBRIUM IN THEIR NNEW POSITIONS IN THE AREAS BETWEEN THE PRONGSWHERE THEY DEFINNE SAID PREDETERMINED PATTERN OF HOLES.